TOF-SIMSTime-of-Flight Secondary Ion Mass Spectrometry

Time-of-Flight Secondary Ion Mass Spectrometry (TOFSIMS) provides elemental, chemical state and molecular information from surfaces of solid materials. TOF-SIMS is accomplished by exciting a samples surface with a finely focused ion beam which causes secondary ions and ion clusters to be emitted from the samples surface. A time-of-flight analyzer is used to measure the exact mass of the emitted ions and clusters. From the exact mass and intensity of the SIMS peak, the identity of an element or molecular fragments can be determined.

ToF-SIMS instruments typically include the following components: - An ultrahigh vacuum system, which is needed to increase the mean free path of ions liberated in the flight path; - A particle gun, that typically uses a Ga or Cs source; - The flight path, - The mass detector system.

The average depth of analysis for a TOF-SIMS measurement is approximately 1 nm. The ultimate spatial resolution can reach around 0.1 µm. Spatial distribution information is obtained by scanning a micro focused ion beam across the sample surface. Depth distribution information is obtained by combining TOF-SIMS measurements with ion milling (sputtering) to characterize a thin film structure. In addition, our TOF-SIMS instrument provides a unique 3D analysis capability that combines in-situ focused ion beam sectioning (FIB) with high mass resolution and high spatial resolution imaging (HR) to provide 3D chemical characterization.

The information TOF-SIMS provides about various samples is important for many industrial and research applications where surface or thin film composition plays a critical role in performance including: nanomaterials, photovoltaics, polymer surface modification, catalysis, corrosion, adhesion, semiconductor devices and packaging, magnetic media, display technology, thin film coatings, and medical materials used for numerous applications.

The following example is related to energy storage, more specifically Li-ion batteries. In this field, the characterization of electrode/electrolyte interfaces is essential to understand the electrochemical performances of cells. The 3D image represents the elemental distribution (of the negative electrode from a full cell LiMn2O4/Li4Ti5O12) of Mn, LiF and Ti. J.B. Gieu, C. Courreges, H. Martinez, J. Phy. Chem C 2016